RD-180 Engine: An Established Record of Performance
and Reliability on Atlas Launch Vehicles
Brooke Mosley
United Launch Alliance
Littleton Colorado
Abstract— Expendable Launch vehicles remain the primary
means of delivering payloads to orbit. 1 2 High reliability in
these systems is vital to the safe delivery of the valuable
payloads they carry. A considerable number of past launch
vehicle failures can be attributed to propulsion subsystems.
These subsystems contain combustion, control thrust levels,
maintain vehicle stability, and withstand the dynamic loads
associated with these processes. The high levels of
complexity associated with propulsion subsystems often
provide opportunities for failure.
mission performance demonstrated by the RD-180 has
defined it as a mature, reliable, flight proven system.
TABLE OF CONTENTS
1. INTRODUCTION ................................................................ 1
2. HISTORY .......................................................................... 1
3. RD-180: UNMATCHED COMBINATION OF
PERFORMANCE AND RELIABILITY ...................................... 2
4. RD-180 CONTINUES TO IMPROVE ................................... 3
5. RELIABILITY THROUGH ATLAS EVOLUTION.................. 3
6. TURNING PROGRAM LIMITATIONS INTO PROGRAM
SUCCESSES ........................................................................... 4
7. SUCCESS IN DATA SHARING ............................................ 5
8. SUMMARY ........................................................................ 6
REFERENCES........................................................................ 6
It is crucial for launch vehicle providers to utilize reliable
and robust propulsion systems to propel customer payloads
to their final destination. Reliability is enhanced by
establishing a mature design and is proven by demonstrating
performance through testing and flight. Propulsion system
improvements are inherent to any program where the
ultimate goal is technical excellence and high reliability.
The Atlas launch vehicle’s main booster engine, the RD180, has demonstrated consistent performance with
predictable environments over the past decade. The RD180 has substantially contributed to the established a record
of high reliability on Atlas launch vehicles since its debut
on the Atlas III in May of 2000.
1. INTRODUCTION
In 1997 Lockheed Martin established an agreement with
NPO Energomash, the leading Russian developer of liquid
propellant rocket engines, to purchase engines for Atlas
launch vehicles. The Russian American collaboration
required to make these flights successful has surmounted
significant challenges and withstood the test of time. RD180s are delivered to ULA, a 50/50 joint venture owned by
Lockheed Martin and The Boeing Company, via an
American Russian joint venture company RD AMROSS.
RD AMROSS is a 50/50 joint venture between Pratt &
Whitney Rocketdyne (PWR) and NPO Energomash (NPO
EM). NPO EM is the designer and manufacturer of the RD180. PWR is the premier U.S. liquid rocket engine
developer selected to collaborate with NPO EM in support
of the RD-180 program. PWR and NPO EM both provide
RD-180 integration and launch support services to ULA.
Ten years after the debut of the first Atlas launch with an
RD-180 twenty-nine engines have flown and have exhibited
consistent performance.
The RD-180 is a LOx rich, closed cycle, staged combustion,
LOx Kerosene engine, with throttle capability from 47% to
100% power level.
The closed cycle engine with
continuous throttling provides an unprecedented advantage
to vehicle performance and mission profile flexibility, while
still providing a very reliable engine design. To date,
twenty-six engines have flown on missions out of Cape
Canaveral Air Force Station, and three have flown on
missions out of Vandenberg Air Force Base. These
launches delivered payloads for commercial customers,
NASA, NRO, and the USAF.
The engine integration to the Atlas V booster and
subsequent testing is performed by United Launch Alliance
(ULA) at the integration facility and launch sites. A greater
understanding of the RD-180 engine system has been
acquired by ULA, over the last twenty-nine launch
campaigns.
This
understanding
of
operational
characteristics including engine to engine variability
associated with a family of engines has allowed
development and implementation of enhanced ground
testing, and operational risk reductions. The continuous
1
2
2. HISTORY
In the early 1990s the closed cycle, LOx rich, staged
combustion technology rumored to exist in Russia was
originally sought out by General Dynamics because engines
of this kind would be able to provide a dramatic
performance increase over available U.S. rocket technology.
Unlike its rocket building counterparts in the United States,
Europe, China, and Japan, Russia was able to master a
unique LOx rich closed cycle combustion technology which
delivered a 25% performance increase4 .
978-1-4244-7351-9/11/$26.00 ©2011 IEEE
IEEEAC paper#1457, Version 2, Updated 2011:1:13
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3. RD-180: UNMATCHED COMBINATION OF
PERFORMANCE AND RELIABILITY
There was skepticism in the reliability of the newly found
Russian technology as it was such a departure from designs
in use in the United States; the LOx rich staged combustion
cycle engine, although it delivered performance
improvements, was considered too risky not only in the U.S.
but around the world. The staged combustion cycle must
achieve far higher combustion pressures in the chamber
than open cycles because the main combustion chamber
receives high pressure gaseous oxygen directly from the
turbine exhaust. The end result is higher performance
however the reward comes with additional risk.
For the RD-180, all of the oxygen flows through the
preburner which drives the turbine. The gaseous oxygen
that flows to the chamber requires much less energy to
initiate a combustion process so the engine is more prone to
consuming itself given an ignition source.
NPO
Energomash, the leading designer of engines in Russia, had
gone through hundreds of designs, each an improvement on
the last, to harness the power of LOx rich combustion. This
required a very careful approach to how the fuel is burned
in the preburner so that the temperature field is uniform. It
also required improvements in materials and production
techniques. They found a way to take the chamber
pressures to new limits while protecting the internal
components from fire risks. This required a new class of
high temperature resistant stainless steel invented to cope
with the risks of the LOx rich environment3.
Figure 1 – AV-025 29th Atlas launch with an RD-180
To achieve this additional performance, staged combustion
engine designs require a much better understanding of the
combustion process and the stages of that process. The
engine is the subsystem responsible for containing and
controlling combustion. For a LOx rich process, where
environments include much higher pressures and
temperatures, it is imperative to be able to limit where these
processes take place. The unique technology developed for
the RD-180 sets it apart from its counterparts designed in
the United States not from a combustion understanding
standpoint but by the technology developed to mitigate
combustion.
The RD-180 designed and built by NPO EM was
specifically tailored for the Atlas launch vehicle. It is a two
chamber derivative of the RD-170 which later evolved into
the RD-171 and RD-171M. Before agreeing to purchase
these engines United Launch Alliance had to be persuaded
that it worked and could work reliably. This was achieved
through rigorous development and certification testing that
was agreed upon by all parties involved. Since each side
had a vested interest in the success of the engine, it was
imperative that each side had the answers to their questions
and were satisfied with the level of testing conducted.
Extensive development was necessary to create the
combustion devices, the preburner and the chambers, that
were able to consistently control continuous throttle from
47% to 100%. This technology was developed by the
Soviet Union beginning in the 1970s at the height of the
space race, and required significant resources. Learning
how to control this type of process meant burning up a lot
of hardware. With the space race in full effect the Russian
designers had unlimited resources. They were able to
develop this unique design though a pragmatic hardware
based approach where important design questions were
resolved after full system tests. 3
The demonstrated performance established during this
process was beyond anything achieved in the United States.
The RD-180 reaches chamber pressures up to 3,722psia
which was more than double the chamber pressures
achieved by comparable U.S. engines. Exposure to Russian
design philosophy and the success of a high performance
engine made U.S. engine designers question their own
methods.
This dual sided cross-cultural engineering
approach which has persisted through the life of the RD-180
program adds depth to the understanding of engine
capability and operational characteristics.
After the fall of the Soviet Union, word of what the
Russians had been able to accomplish made it into the
global aerospace community and the technology was sought
out by General Dynamics which later merged with Martin
Marietta and eventually became Lockheed Martin. Twenty
years after the technology had been developed it was still
largely misunderstood by the global community and
considered too risky.
In Russia the manufacturing organization is allowed more
flexibility in recommending changes to the design process.
2
This allows for greater innovation in process and
manufacturing techniques. In the U.S., in general, designs
are delivered to the factory floor and the manufacturing
engineer must meet the requirements specified on the
drawing with substantial oversight by the designers. This
increases time to delivery, scrap rate, requires higher
precision manufacturing, and ultimately increases cost.3
also shown an ability to be successful in foreign markets,
not only with the Atlas program but with Boeing’s Sea
Launch and South Korea’s Naro 1.
International
cooperation in technical programs does have risks and
challenges, but based on the consistent performance of the
Atlases powered by the RD-180, those challenges have not
impacted the most important end result – mission success.
This has established that leveraging off of foreign
technologies which are either superior or better suited to a
specific system can provide significant benefits to a
program.
Understanding and acceptance of differences in design and
manufacturing
methods
was
established
during
development and certification testing and has been
solidified by the successful launches over the last decade.
With proof of consistent performance from test, and
established reliability in flight, the Atlas program has been
able to leverage off of the best rocket engine technology in
the world. To date there have been twenty-nine Atlas
vehicles flown with the RD-180.
Those launches
accumulated a total of 6,973 seconds, almost two hours, of
booster engine run time.
For the Atlas those benefits include a 47%-100% throttle
capability and up to 860,000 lbs of thrust. Aside from the
original benefits delivered with the engine, long term
benefits have also become apparent. The RD-180 engine
has shown repeatable ignition and cutoff, stable
combustion, predictable thermal and dynamic environments,
as well as consistent engine control accuracy in mixture
ratio, thrust levels, and trajectory.
This consistency in
engine performance adds confidence to vehicle margins,
component assessments, and performance models.
4. RD-180 CONTINUES TO IMPROVE
No development program or new program performs
consistently and with perfection.
But the RD-180
development was fortunate in that most of the design
deficiencies had been worked out on its predecessor engine
which, at the time of the development of the RD-180, had
already gone through the growing pains of its own
development and had flown upwards of twenty-six flights
on the Zenit launch vehicle.
5. RELIABILITY THROUGH ATLAS EVOLUTION
When the RD-180 was chosen as the boost phase
propulsion system for the Atlas III, the overall reliability of
the Atlas rocket increased from 0.9876 to 0.9955. This
increase was largely due to the reduction in the number of
engines on the booster. The Atlas IIAS vehicle relied upon
six MA-5 engines during the boost phase. When the
number of propulsion systems was reduced from six to one
during the evolution from Atlas II to Atlas III, the reliability
coefficient improved dramatically. There were changes to
the Centaur upper stage and the RL10 that were also
improvements in reliability, but these were very minor in
comparison to the transition to a single propulsion system
on the first stage. Every successful launch improves the
overall reliability number by a very small amount. More
important than this small improvement is the confidence in
the original numbers and the assumptions used to establish
them.
The current version of the RD-180 flies at 100% of its thrust
capacity and has slightly higher chamber pressures than its
predecessor engine4. It is built from 70% similar
components. The other roughly 30% are scaled versions of
the RD-170 components.
The RD-180 reliability is
enhanced not only by its heritage but also by its current
place in a family of NPO Energomash engines the RD171M and the RD-191.
Under the license agreement
between NPO EM and the ULA, there is very limited scope
on the ability to convey information from the other
programs. However continuous hardware and process
improvements are inherent to any program where technical
excellence and product success are key factors. This is a
benefit to RD-180 because not only does it improve from
the knowledge gained by its own tests and flights but also
by the testing and flights of the RD-171M and RD-191.
Although ULA and PWR do not have insight into what
design improvements are conducted on the other programs,
it is quite clear based on the understanding of engineering
practice and the history of success at NPO Energomash that
product improvements cross program lines.
The reason for the Atlas vehicle success is largely due to the
deep roots and hard won maturity in the areas of system
design robustness and process discipline that are results of
an evolved vehicle design4. Like our Russian counterparts,
this type of evolved process comes from experience. That
experience being mostly a result of understanding and
recovery from past failures in addition to past successes.
Years of monitoring both in ground test and flight has
provided a substantial family of data. The process for data
collection and review is rigorous; new data compared to an
established family applies directly to improved reliability.
Continuous post flight analysis leads to corrective actions,
Based on the success of the RD-180 since its debut over ten
years ago, NPO Energomash has not only continued to
establish their superiority in engine design but they have
3
lessons learned, and model refinements.
improvements to the Russian company that builds the
engine. The RD-180 program must adhere to international
traffic in arms regulations or ITAR. ITAR restrictions on
the RD-180 program limit the constant operational
improvement that naturally occurs on other domestic
programs. In order to do business with a foreign company,
United Launch Alliance and its counterparts at Pratt &
Whitney Rocketdyne must operate under a license
agreement with NPO Energomash approved by the United
States Government. The purpose of this agreement is to
protect sensitive technology that is available in the United
States but not available in Russia. NPO EM has a similar
agreement with the Russian Government that only allows
While there are improvements on the engine supplier side,
there are also improvements related to integration and
launch. When the RD-180 is delivered the thrust frame and
the gimbal actuators for thrust vector control are already
installed. This makes for a very simple integration process.
Streamlining and adding improvements to these processes
have occurred over the life of the program and were a real
benefit to ULA during the move of its production facility
from Denver Colorado to Decatur Alabama.
Decade of RD-180 Flights
30
25
Number of Flights
20
15
10
5
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Figure 2 – RD-180 engines flown between 2000 and 2010
them to provide information and data specific to the RD180 engine. The U.S. license must be agreed upon by NPO
EM the U.S. government and ULA. Likewise, the PWR
license must be agreed upon by NPO EM and the U.S.
government. This document is what defines the scope of
technical assistance and discussions that may be provided
by ULA and PWR to NPO EM in order to deal with issues
associated with integration and launch of the engines.
6. TURNING PROGRAM LIMITATIONS INTO
PROGRAM SUCCESSES
A better understanding of the engine system over time has
led to the development of enhanced testing, support
equipment, and test hardware. Despite the enhanced
understanding and comfort that come with a mature
program, there are known disadvantages associated with a
foreign supplied engine.
Often times the license and ITAR regulations limit the type
of discussions and data transfers that take place between
NPO Energomash, United Launch Alliance, and Pratt &
Whitney Rocketdyne.
ITAR Restrictions
Although ULA is the end user of the engine, as a U.S.
company, it is not authorized to suggest technical
4
Despite this challenge, there has been an enhancement of
communication since the program began. Over time the
license or technical assistance agreement has undergone
revisions and improvements. These revisions have not
necessarily increased or decreased the scope of what is
allowed, but the restrictions have become better defined and
better understood by all parties. Typically a technical
license defined or agreed upon by the U.S. government
expires between ten and twelve years. Revisions are added,
relationships between companies, and relationships between
governments change. After sixteen years, the RD-180
technical assistance agreement expired, and was replaced
with a new re-baselined consolidated license in 2009.
obligations, time differences, and a translator in between
makes the conversation very formal. The time to develop
relationships is harder, it takes longer, and requires
considerably more effort from all parties. Fortunately
everyone has the same goal: success of the hardware. When
that success comes to fruition the reward is more personal in
spite of or even because of the challenges that are overcome
along the way.
7. SUCCESS IN DATA SHARING
One very common misperception related to the RD-180
program is that our Russian colleagues are prone to
withholding or guarding information; this would be
understandable if it did occur this way. It would be a
natural reaction to protect technology that you know far
surpasses that of your competitors however quite the
opposite is true. An agreement was made to provide
engines, along with their data, and engineering support that
leads to their successful use and consistent performance.
True to that agreement over the past ten years, that delivery
has been made. Information that is critical to successful
engine operation is always provided.
The RD-180 program adheres to the restrictions that are
intended to control the export and import of sensitive
technical information between countries. To ensure that
this is done, there has been involvement of the Defense
Technology Security Administration or DTSA. In the past
all operations that required support in the production factory
from Russian foreign nationals and meetings conducted in
Russia had a DTSA representative present. Over time ULA
and its partners have been proactive in training and self
monitoring which has led to less oversight by DTSA. Most
meetings in the factory in Decatur Alabama and at NPO
Energomash in Khimki Russia are conducted under
company internal monitoring and the DTSA monitor
requirement is waived. This has delivered considerable cost
savings to the United States Government.
NPO Energomash Supplier Visits
Russian culture and American culture are quite different.
At the same time, the engineering communities are very
similar on many levels. It is a skeptical community, one
where solutions to problems are based on analysis rooted in
math and physics or results of testing and inspections.
NPO EM has been very gracious in their willingness to
share information in order to help its customer succeed.
Non-technical visits to NPO EM suppliers in more recent
years have provided an increased transparency. In 2008
ULA, PWR, and the USAF customer were able to visit the
RD-180 thrust vector control actuator supplier, Arsenal in
St. Petersburg. In 2010 a similar visit was coordinated with
the chamber manufacturers at Metalist in Samara. This
increased openness has allowed more opportunity for
dialogue, and has enhanced not only the relationship with
NPO EM but their suppliers as well.
International Challenges
The RD-180 program deals with several real every day
challenges. The time zone is a perfect example. There is a
ten hour time difference between U.S. Mountain Time in
Denver, Colorado and Russian Moscow Time in Moscow,
Russia. Meetings and correspondence must be arranged at
specific times in order to support this significant time
difference. Travel to the supplier or supplier travel to ULA
facilities involves overcoming significant jetlag prior to
showing up for work.
International travel comes with its own difficulties and
expenses, with business visas, customs, and long plane
rides. Thus, travel is limited to what is absolutely
necessary.
History of Transparency: Co-Production
It is important to note that transparency is not new to the
RD-180 program. In September of 2003 all of the
documents required to build the RD-180 engine were
delivered to RD AMROSS and PWR in West Palm Beach
in support of U.S. co-production of the RD-180. The
shipments included more than 100,000 documents that
represented the data required to produce the engine. That
data included engineering drawings, design specifications,
certification design documentation and manufacturing
documentation, in addition to materials data, test data and
tooling documentation5.
Language barriers limit the ability to communicate issues
and ideas. Engineers are forced to get creative with the
words used to communicate in order to get a point across or
must find more than one way to convey a particular idea.
Sometimes it is difficult to understand how or why
something is done in a particular way because of differences
in cultures. We do things very differently both in business
and in engineering. Effective communication is often about
relationships. Some of the best communication happens
when the conversation or the relationship is less formal.
The frame of the RD-180 program with ITAR, contractual
This information did two things. First it allowed U.S.
engineers insight into the design techniques, practices, and
5
metallurgy which led to a better understanding and a greater
appreciation of the RD-180 engine system. Second and
more importantly the delivery of all the RD-180
documentation reinforced the relationship between Pratt &
Whitney Rocketdyne and NPO Energomash. There was a
promise made to deliver the data and the extensive amount
of data was delivered. The value of the intellectual property
rights transferred was enormous. This both exposed and
established mutual trust between the companies.
It
solidified their ability to establish international cooperation,
trusting that there would be protection of very valuable
intellectual property.
4
Houlguin, “ELV Human Rating: Atlas Heritage and
Future Potential,” AIAA Tracking Number 33343 Paper
Number: 3812 Session: VS-3 Exploration Launch Vehicle
Concepts.
5
“Major Step Complete and Next Phase Accelerated for
Production of U.S. Built LOx/Kersosene Oxygen Rich
Staged Combustion Rocket Booster Engine”. United
Technologies Corp. Pratt & Whitney, West Palm Beach, FL
2010
Sept
24,
2003
Web.
October
1st,
<http://www.pw.utc.com>
8. SUMMARY
[6] NPO Energomash Web site
http://www.npoenergomash.ru/eng/
The RD-180 program has established that international
cooperation, involving valuable intellectual property, is
possible and can be beneficial to all parties involved. Using
a powerful, efficient, reliable engine on an already mature
launch vehicle has created a pairing which has led to years
of mutual success.
[7] Spaceflight Now “Historic South Korean Satellite Launch
Fails”. By Stephen Clark August 25th, 2009 Web October
1st 2010 <
http://spaceflightnow.com/news/n0908/25kslv/>
This was accomplished despite the initial skepticism that
came with a foreign technology. The risks both in
international relations and the lack of technical
understanding by ULA were accepted or mitigated to allow
use of what was advertised as superior technology. Testing
demonstrated performance which has remained consistent
throughout a decade of Atlas flights. Partners at NPO EM,
PWR, RD AMROSS and ULA have established a strong
understanding of the engine not only technically but
programmatically. Continuous improvements, built upon a
strong heritage with growing experience and enhanced
openness and communication are well recognized
throughout the RD-180 program.
ITAR restrictions, DTSA involvement, and Language
Barriers, to name a few, are the hurdles that had to be
overcome by ULA and its partners to leverage the power of
the RD-180 engine. A history of well developed engines,
proven performance, and substantial support from the
engine supplier has set precedence for international program
cooperation. This cooperation was formed in order to give
the Atlas rockets increased performance and reliability
through use of the RD-180 as the main booster engine.
REFERENCES
3
“Engines That Came in from the Cold”. By Dan Clifton
Equinox TV Series. Original Air Date: 1 March 2001
6